1. Field of the Invention
The present invention relates in general to a telephone set (a combination of a telephone transmitter and a telephone receiver) adapted to receive two or more call signals having different patterns which call respective telephone numbers. More particularly, the present invention is concerned with improvements in such telephone set wherein the patterns of such call signals are registered in relation to the telephone numbers, so that the telephone number called by each call signal received from a calling party can be recognized by the telephone set of a called party.
2. Discussion of the Related Art
There is known a telephone set adapted to utilize a so-called "distinctive ringing service (D/R service)" available from a telephone exchange company. This telephone set of distinctive ringing type uses two or more telephone numbers on one telephone line. The distinctive ringing service provides the telephone set with telephone call signals which have different patterns as illustrated at (a) through (d) in FIG. 17, when the respective telephone numbers are called by a remote telephone transmitter of the calling party, so that the ringing device of the facsimile system of the receiving or called party generates different types of ringing sound depending upon the telephone numbers called.
Where such a telephone set of distinctive ringing type is incorporated as a telephone portion of a facsimile system, one of the telephone numbers is used exclusively for facsimile communication with a facsimile portion of a remote facsimile system, while the other telephone number or numbers is/are exclusively used for telephone communication with a telephone portion of the remote facsimile system. The telephone number called by the remote facsimile system of the calling party can be recognized by the specific type of the ringing sound generated according to the specific pattern of the appropriate call signal received at the called party. Alternatively, one or more telephone sets of distinctive ringing type connected to one telephone line can be effectively used by two or more users to which respective different telephone numbers are assigned.
One proposed telephone set of distinctive ringing type includes memory means for storing the patterns of the call signals corresponding to the respective telephone numbers, comparing means for comparing the pattern of each received call signal with the stored patterns, pattern determining means for determining the telephone number called by the received call signal, on the basis of a comparison by the comparing means, and processing means for effecting a processing operation according to the telephone number determined by the pattern determining means. Where this telephone set is used in a facsimile system wherein one of the telephone numbers is assigned to receive a facsimile signal from the calling party, for example, the pattern of the call signal corresponding to that facsimile reception telephone number is registered or stored in memory means as the facsimile reception pattern, so that the facsimile signal received with the call signal is automatically processed for recording of an image represented by the facsimile signal, when the pattern of the received call signal is the same as the registered facsimile reception pattern. An example of such facsimile system is disclosed in JP-A-4-58855.
The facsimile reception pattern of the call signal calling the facsimile reception telephone number is registered by the user by listening to the ringing sound generated according to that received call signal. For example, a plurality of telephone numbers used for a telephone set of distinctive ringing type are called by call signals which have different patterns as indicated at (a) through (d) in FIG. 17. One of these patterns is selected and registered as the facsimile reception call signal pattern. The call signal indicated at (a) has only one ON state per period. The call signal indicated at (b) has two ON states per period. The call signal indicated (c) has three ON states per period, which consist of a first short ON-time, a second short ON-time and a third long ON-time. The call signal indicated at (d) has three ON states per period, which consist of a first short ON-time, a second long ON-time and a third short ON-time. To register one of these call signal patterns as the facsimile reception pattern, the following method is considered. That is, all of these patterns are first stored in memory means, and the call signal calling the facsimile reception telephone number is received from a telephone exchange company upon calling from a remote telephone or facsimile transmitter as the calling party. The user of the telephone set of the called party recognizes the pattern of the received signal by listening to the ringing sound generated according to the ON-OFF pattern of the received call signal, and selects the corresponding one of the stored call signal patterns as the facsimile reception pattern. This way of registering the facsimile reception pattern requires the user to simply select one of the stored patterns which corresponds to the type of the ringing sound generated upon reception of the call signal calling the facsimile reception telephone number.
However, it is difficult for the user to correctly distinguish the pattern of the received call signal (facsimile reception call signal) from the patterns of the other call signals, by listening to the ringing sound corresponding to the received call signal. In the example of FIG. 17, it is rather difficult to distinguish the three-ON-state patterns indicated at (c) and (d) from each other, since both of these two patterns have three ON states. Accordingly, the user may incorrectly recognize the pattern of the received call signal and selects the wrong pattern as the facsimile reception pattern corresponding to the facsimile reception telephone number. Described more specifically, it is easier to distinguish the different patterns (c) and (d) from each other by listening to the ringing sounds corresponding to these different patterns, than by listening to the ringing sound corresponding to only one of these patterns. In other words, it is difficult for the user not familiar enough with the ringing sounds, to correctly recognize the pattern of the received call signal by simply listening to the ringing sound of the received call signal only. Some telephone exchange companies use two or more different two-ON-state call signals which have different combinations of ON-times and OFF-times and which may include the pattern as indicated at (b) in FIG. 17. In this case, too, the user feels difficulty in correctly recognizing the pattern of the call signal which is received for the purpose of registering the facsimile reception call signal pattern. Some users do not even know the patterns of the call signals.